Maybe Ainu or Inuktitut or Cree or any of those polysynthetic languages...
Also Basque and/or Cantonese or any of the Sinitic languages besides Mandarin. Also maybe an Altaic language like Buryat or Manchu.

Perhaps Tibetan too...

I've always wanted to learn Czech. It just sounds so whimsical, and it's not as harsh sounding as I expected.

Also, every time I hear my Russian friend speak, it makes me want to learn Russian too.

No clue. Manx, maybe. I'd say Welsh, but I'm already sort of learning it anyway and if I wanted to learn it seriously I could probably do it. Chinese (whatever kind) would be nice to know, but I probably wouldn't ever use it and the tones scare me a little.
And, of course, it would be really nice to know Spanish a little better, but that doesn't count because I sort of know that too. Less sort of than Welsh, that is.
If you're allowed to include conlangs here, I'd love to become fluent in all my conlangs, but I don't have the time or the determination.

Haws dweud mynydd na mynd drosto.

More sort of than that! I know a total of one sentence in Welsh: "Bore da, blant!" (Good morning, children!) Don't post in Welsh and expect me to understand it. Really. I'm sorry I said anything. Just forget it!
(At least, I assume what you wrote was in Welsh. Please correct me if I'm wrong. See? I can't even identify it by looking at it! )

Okay, I know another sentence: Dwi'n dy garu, 'nghariad. (I love you, dearest -- or something to that effect.)
All in all, I can't use Welsh for any meaningful communication. I'll be back tomorrow (or whenever I get to it) with the translation of Linguoboy's post. All refeir.

Would love to be able to use French for other sentences than "Pourquoi ma barbe ne sent pas la noix de coco", etc.

Well, I just translated this, and here is what Google Translate said: "Easier said than mountain passes." I assume that means "easier said than done". Am I right? If so, thanks for telling me what I already know. Bore da, y Ddraig Goch!
Edit: Actually, it strikes me as somewhat presumptuous to expect me to understand a post in Welsh and to understand the idiom(s) in it. The implication of it seems to be, "if you can't understand this, then you don't appreciate how hard it is to learn Welsh and you're never going to". Bah. I didn't even mean "learn Welsh" -- I meant "understand it sort-of and be able to write in it sort-of".

You didn't translate it; you had it translated. Google Translate did all the heavy lifting, then you made a (lucky) guess.

Literally, the proverb is "Easier to say mountain than to go across it". Perhaps you could "seriously" learn Welsh if you wanted to. But, as the Welsh say, ni heuir ni fedir! (Good luck getting Google to translate that one!)